UNITED NATIONS, May 5 (Xinhua) -- Gunfire stopped distribution of food in a besieged Palestinian refugee camp on Monday, a United Nations spokesperson confirmed, reiterating demands that the UN agency assisting Palestinian refugees be allowed to safely and without interruption distribute substantial quantities of food and other humanitarian assistance inside Yarmouk.

The spokesman, Chris Gunness, said the UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) distributed food parcels to only 162 civilian families earlier on Monday.

"The UNRWA team arrived at the Bateekhah northern entrance to Yarmouk at 10:00 and was permitted to commence distribution inside Yarmouk at 12:00," Gunness said.

"Distribution continued at a relatively slow pace until 15:00, when two gunshots impacted the area of the northern Bateekhah entrance, close to UNRWA vehicles and support staff," he said.

The gunfire injured at least one civilian bystander, and forced the UNRWA team to withdraw and return to its field office.

"Today's incident highlights the ongoing risks faced by civilians and humanitarian personnel in Yarmouk and other contested areas," Gunness said in a statement following the shooting.

He underscored that "all sides must demonstrate commitment in address the grave humanitarian crisis endured by civilians inside Yarmouk" and that all parties also have a responsible to protect civilians.

While acknowledging the Syrian authorities' assistance in the Monday distribution, Gunness said that UNRWA remains seriously concerned that its efforts are frequently delayed or interrupted.

"Over the last three days, the number of civilian families who have received food parcels is extremely low when compared to the thousands of families in urgent need of UNRWA humanitarian assistance, due to the closed status of Yarmouk," he said.

UNRWA has appealed to the Syrian authorities to expand their support to facilitate "regular, substantial, safe" food distributions in Yarmouk and to authorize the distribution of a full range of humanitarian assistance, particularly medicines and medical supplies.

Prior to the armed conflict in Syria, which began in March 2011, Yarmouk was home to more than 160,000 Palestinian refugees. Since December 2012, fighting has caused at least 140,000 Palestine refugees to flee their homes in Yarmouk, as armed opposition groups established a presence in the area, with Government forces controlling the periphery.